Research On Wetting Behaviors Of Molten Metals On Different Orientation Single Crystal Al₂O₃ Substrates In High Magnetic Fields

Aluminum matrix composites combines the advantages of metals and ceramics,and have broad applications in microelectronics manufacturing,heterogeneous catalysis,automotive heat resistance,and insulating parts.In the process of preparing aluminum matrix composites,the wettability between the metal melt and the ceramic substrate determines the manufacturing quality and material performance.Up to now,the researchers have done a lot of research on the wettability of molten aluminum and aluminum-copper alloy on alumina substrates by changing the substrate orientation,temperature,active elements and atmosphere.However,wettability has not been significant improved by changing wetting affecting factors.Therefore,it is imperative to explore a new way to improve the wettability of the metal melt on alumina substrate.As a non-contact physics field,high magnetic field has been widely used in material processing in recent years.At the same time,high magnetic field can affect the surface tension of liquid which is one of the important parameters affecting wettability.Therefore,pure Al and Al-2wt.%Cu alloys were selected as the melt,and single crystalα-Al2O3 was used as the ceramic substrate.The effects of temperature,substrate orientation,magnetic flux density and active element on the contact angles of Al/Al2O3 and Al-2wt.%Cu/Al2O3 systems were investigated by sessile drop method combining with optical microscopy,SEM,XRD,AFM and other detection methods.The main research contents are as follows:(1)The contact angle of Al and Al-2wt.%Cu melts on the Al2O3 substrate reduces under high magnetic field,and the degree of decrease is related to the magnetic flux density.When the magnetic flux density is increased to 6 T,the contact angle reaches the smallest value.At this moment,the contact angle of Al/Al2O3 and Al2wt.%Cu/Al2O3 systems is reduced by 49.6° and 52.0°,respectively,compared to the magnetic flux density of 0 T.(2)The effect of the high magnetic field on the wettability between Al/Al2O3 and Al-2wt.%Cu/Al2O3 is related to the crystal orientation of the Al2O3 substrate.The contact angle of the molten metal on the(0001)orientation substrate is relatively large,and the contact angle of the molten metal on the(0112)orientation substrate is relatively small.(3)The effect of the high magnetic field on the wettability between Al/Al2O3 and Al-2wt.%Cu/Al2O3 is related to the temperature and the addition of Cu element.The increase of temperature is beneficial for improving the wettability and the diameter ratio of molten metals.The addition of Cu element has different effects on the wettability with the change of the magnetic flux density and the orientation of the substrate.(4)Wettability of Al/Al2O3 and Al-2wt.%Cu/Al2O3 systems change because of the difference in magnetic susceptibility between different orientation Al2O3 substrates,the difference in bond energies between the Al-Al bond and the Al-O bond,the difference in melt convection,and the difference in melt viscosity under high magnetic field.